TY  - JOUR
AU  - Zaid, Adeeb
AU  - Al-Ziyadi, Husam
AU  - Wekalao, Jacob
AU  - Maity, Prasenjit
PY  - 2026
DA  - 2026/09/11
TI  - Bridging the Gap Between Laboratory Efficiency and Real Wastewater Performance: A Critical Review of Rare-Earth-Doped Metal Oxide Photocatalysts for Dye Degradation
JO  - Catalysis Research
SP  - 011
VL  - 06
IS  - 03
AB  - Photocatalytic degradation of organic dyes using semiconductor materials has been widely investigated for wastewater treatment. Yet, high activity reported under controlled laboratory conditions does not necessarily translate into practical treatment performance. This review evaluates the hypothesis that rare-earth (RE) doping can improve metal-oxide photocatalysis and examines whether the reported improvements are supported by adequate mechanistic evidence and relevant practical validation. A structured literature search of Web of Science and Scopus identified 29 studies of RE-doped metal oxides for dye degradation. The analysis considered catalyst composition, dopant concentration, morphology, synthesis route, operating conditions, photocatalytic kinetics, mechanistic characterization, mineralization, stability, leaching, and real-wastewater testing. Reported removal efficiencies ranged from 77 to 100%, with a mean of 92.9%; however, these values were not used to rank catalysts because experimental conditions differed substantially. Mechanistic evidence was classified as direct in 15 studies (51.7%) and partial in 14 (48.3%). PL and XPS were widely reported, whereas EIS and ESR/EPR were used less frequently, indicating that proposed charge-transfer and reactive-species mechanisms are not consistently supported by complementary evidence. TOC analysis was reported in 10 studies (34.5%), none reported apparent quantum yields, and none tested RE-doped photocatalysts with real wastewater. Stability or reuse testing was reported in 20 studies (69.0%), while quantitative rare-earth leaching was reported in only one study (3.4%). These findings show that RE doping can modify photocatalyst properties, but its practical value cannot be established from dye-removal efficiency alone. Standardized reporting, mechanistic validation, real-wastewater testing, long-term stability and leaching assessment, and pilot-scale evaluation are required to advance RE-doped photocatalysts toward reliable wastewater treatment.
SN  - 2771-490X
UR  - https://doi.org/10.21926/cr.2603011
DO  - 10.21926/cr.2603011
ID  - Zaid2026
ER  -